Kubernetes-rest-ex

쿠버네티스 내에서 REST API 통신을 실험하는 예제

실습 환경
- Kubernetes v1.26.3
- Calico CNI
- Spring boot v3.0.6
- jdk 17
- Docker
- Docker Hub
- 우리집

Docker Hub URL

미리 만들어둔 Spring Boot Image를 사용합니다.

Application 구조

앱 동작은 간단합니다. Rest Application이 Hello Application을 rest 요청을 한 값을 그대로 출력하는 Application입니다.

Hello Application 소스 코드 (8080포트)

@RestController
class HelloController {

    @GetMapping("/")
    fun getHello(): String {
        return "Hello Server"
    }
}

Rest Application 소스 코드 (8081포트)

@RestController
class HelloRestController(
    @Value("\${rest.url}") val url: String // rest.url="http://localhost:8080/"

) {

    @GetMapping("/")
    fun getRest(): String {
        val restTemplate = RestTemplate()

        return restTemplate?.getForObject(url, String::class.java) ?: "error"
    }
}

실행결과

당연히 Local에서는 잘 돈다.

이제 쿠버네티스에 배포를 해보자.

apiVersion: apps/v1 
kind: Deployment # hello Application Deployment
metadata:
  labels:
    app: webserver
  name: webserver-hello
spec:
  replicas: 3
  selector:
    matchLabels:
      app: webserver
  template:
    metadata:
      labels:
        app: webserver
    spec:
      containers:
      - image: ghdcksgml1/spring-hello
        name: webserver-hello
        ports:
        - containerPort: 8080
---
apiVersion: apps/v1
kind: Deployment # Rest Application Deployment
metadata:
  labels:
    app: webserver
  name: webserver-rest
spec:
  replicas: 3
  selector:
    matchLabels:
      app: webserver
  template:
    metadata:
      labels:
        app: webserver
    spec:
      containers:
      - image: ghdcksgml1/spring-rest
        name: webserver-rest
        ports:
        - containerPort: 8081
---
apiVersion: v1
kind: Service # LoadBalancer
metadata:
  labels:
    app: webserver
  name: webserver-svc
spec:
  ports:
  - port: 8080
    protocol: TCP
    targetPort: 8080
    name: webserver-hello
  - port: 8081
    protocol: TCP
    targetPort: 8081
    name: webserver-rest
  selector:
    app: webserver
  type: LoadBalancer